1. Field of the Invention
This invention relates to an auger type mining machine used for mining coal and the like, and more particularly, to an auger type mining machine in which sections of auger can be added to the rear portion of the auger in order to extend the drilling distance into the vane of material being mined.
2. Prior Art
Auger type mining machines, particularly those in which short length of auger may be added to the rear portion of the entire auger unit as a seam is being mined, have found considerable favor in the industry and many machines for utilizing sectioned augers have been designed. It is very common for auger type mining machines to utilize a drive unit which attaches to a centrally located shaft in the auger. The power unit is usually designed to provide both the torque necessary to be transmitted to the cutting head to do the mining operation, as well as the necessary advancement in order to keep the cutting head against the face of the seam of material being mined.
The use of a single source for transmitting both the torque and advancement of the auger presents many problems associated with prior art devices. By transmitting the torque through a central shaft in the auger some misalignment and wobbling of the auger will naturally occur due to the inherent bending of such a shaft when torqued by application of a rotational force directly to the rear end of the shaft. In addition, because of the relatively small diameter of the shaft in relation to the overall diameter of the auger and the necessary forces to be transmitted, a substantial amount of power must be utilized to apply the torque to such a small radius arm as that presented by the rear portion of the shaft itself.
Another problem associated with applying both the torque and forward advancement of the augers through a single power unit is the necessary coordination between the rotation and advancement of the auger in order to keep the cutting head adjacent the face being mined. As is the case with many prior art machines of this type the power supplying unit itself is advanced forward towards the surface of the wall so as to maintain the auger in proper relation to the surface being mined. Such as system usually requires a very complicated mechanically coordinated movement between the movement of the auger and the forward movement of the power unit, thus making this portion of the mining apparatus one of the more expensive portions.